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CVE-2026-96940 is a weak-authorization vulnerability in Microsoft Exchange Server that allows an authenticated attacker to elevate privileges over a network. Successful exploitation can expose other users’ mailboxes, including email messages and attachments, within the same organization, but does not permit access across tenant boundaries. Affected releases include Exchange Server 2016 CU23, Exchange Server 2019 CU14 and CU15, and Exchange Server Subscription Edition RTM. Microsoft discovered the vulnerability internally and reported no known active exploitation when announcing the fix.
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No public exploit code observed for this vulnerability.
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37 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A high-severity information disclosure vulnerability in Microsoft Exchange that may expose other users’ emails and attachments to authenticated attackers within the same organization. It does not permit access across tenant boundaries. Microsoft discovered the flaw internally, considers consistent exploitation possible, and recommends promptly installing the September 2026 v2 security update.
A high-severity authorization weakness in Microsoft Exchange Server allows authenticated network attackers to escalate privileges and gain unauthorized access to other users’ mailboxes, including emails and attachments. It does not permit crossing tenant boundaries. The reported CVSS score is 8.8. Microsoft considers exploitation more likely, but the article does not report observed exploitation. Security updates are available; administrators must patch on-premises servers, including Exchange instances used only for management. Microsoft has already patched cloud servers in hybrid environments. Updates for older server versions require an ESU Period 2 subscription. Reported update side effects include HTTP 500 errors for published calendars and ContentEngine deadlocks involving Korean word-breaking rules.
An authorization vulnerability in Microsoft Exchange Server allows authenticated attackers to access other users’ mailboxes, exposing messages and attachments within the same organization. It requires no user interaction, does not cross tenant boundaries, and has a reported CVSS score of 8.8. Microsoft reported no known active exploitation. The September 2026 V2 updates add the fix; the original September updates do not contain this additional protection.
An authorization weakness in Microsoft Exchange Server permits an authenticated attacker to elevate privileges over a network. The advisory does not specify affected versions, exploitation activity, or remediation availability.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
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Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.